I'm having some issues tuning my carb for best performance. I know, this is a worn out topic, but I couldn't find an answer in the tech section...

I have a hard krome exhaust, big k&n intake, 52.5 pilot, 155 main and 1/2 spacer. 2001 6k miles

Great performance between 0-1/4 throttle and at low rpms.

The main issue I'm having is that at around 3-4krpm, with 3/8-1/2 throttle, the bike hesitates and jerks back and forth. I would put it in 3rd, and give it half gas steady. It accelerates modestly, but at around 3.5k, there is a clear loss of power and jerky hesitation. No popping or other sounds. Does this mean I have too little or too much spacer removed?

Also, I have to make sure, the dimple in the plate that goes over the white spacer faces TOWARDS the spacer, making contact with it, correct?  

How's the top end?

If that's ok, then shave a little more off the spacer.

You should get the main sorted out before messing with the white spacer.  It will affect the results.

By all means, try...... and answer the question at the bottom before hacking any farther,.....making sure you're going in the right direction.
If choking improves it, then less spacer may fix it.

I can only tell you that I had the same surging problem, only at a much lower RPM range, and the 1/2 spacer mod fixed it perfectly.

Serowbot wrote on 02/21/11 at 11:28:17:

Thanks!  I'll let you know how it rolls.....when it gets a shade north of 18 degrees out!  

I just realized,.. it's probably freezing cold where some of you are... ...
It's generally better to do jetting adjustments on days when the temps and humidity are more average for your location...
Jetting in extreme cold or wet is a waste of time, as it will be different when the temps reach normal...  Weather makes a big difference.  All bikes run less than optimum in unusual weather.
You guys might want to hold off for a while.... ...

There is no such thing as perfect jetting,... just a good average for your location and conditions....

Reelthing wrote on 02/24/11 at 09:47:27:


I made sure that was dead on. And I don't adjust anything if it's below 40 degrees.

Also, does the dimple on the metal plate go towards the white spacer, making contact with it, or away from the white spacer, towards the spring? It's the circular-shaped piece that holds the needle in place.

Reelthing wrote on 02/24/11 at 10:20:59:


Soaked in carb cleaner for a few hours and wiped down with microfiber. I guess it could be cleaner, but it wasn't dirty at all. The bowl on the other hand was filthy...then again, the carb was unopened for 10 years...